On Wed, 17 Jul 2019 10:58:49 +0100, Chris Green wrote:

- Need to extend incomer

Do you really mean that or just tails from meter?

Could the incomer, main cut out, meter and isolation switch (if
required, tails 1 m don't IIRC) remain in the shower room?

Mind you I'm not sure that incomer, cut out etc would be allowed in a
shower room in the first place so they may *have* to move. That move
is really down to the DNO (incomer and cutout) and your supplier
(meter). Good luck with that...

- Access above is below floorboards in a cupboard so difficult
wiring

Make floor of cupboard a decent access panel?

Personally I'd look at the entrance hall with the CU inside a
suitably sized cupboard to hide it. If the regs allow THAT these
days...

Failing that the utility room.

--
Cheers
Dave.